Diffuser-integrated prism sheet for backlight units and method of manufacturing the same

ABSTRACT

A diffuser-integrated prism sheet is provided. The prism sheet for backlight units includes a lower diffuser layer having a light diffusion structure, a lower layer formed on the lower diffuser layer, a first intermediate layer formed on the lower layer and having prism-shaped protrusions formed parallel to each other, a second intermediate layer formed on the first intermediate layer, an upper layer formed on the second intermediate layer, and an upper diffuser layer formed on the upper layer and having a light diffusion structure, wherein an air layer is formed between the lower surface of the second intermediate layer and the valleys of the prism-shaped protrusions of the first intermediate layer. Also, a method of manufacturing the diffuser-integrated prism sheet is provided.

CROSS REFERENCE TO RELATED APPLICATION

This application is a division of U.S. patent application Ser. No.12/522,886, filed on Jul. 10, 2009, the disclosure of which isincorporated by reference in its entirety for all purposes.

BACKGROUND

1. Field

The present invention relates to a diffuser-integrated prism sheet forbacklight units and a method of manufacturing the same. Moreparticularly, the present invention relates to a prism sheet forbacklight units, in which diffuser layers are provided on upper andlower surfaces of the prism sheet and prism-shaped protrusions areformed in the prism sheet, and to a method of manufacturing the same.

2. Description of the Related Art

FIG. 1 illustrates the construction of a conventional backlight unit.

As illustrated in FIG. 1, in the conventional backlight unit, afluorescent lamp 1, which is a linear light source, and a lamp reflectorplate 2 for reflecting the light of the fluorescent lamp 1 are disposedto one side of a light guide plate 3 for using the light from thefluorescent lamp 1 as a surface light source, and a reflector sheet 4for preventing the leakage of light is disposed under the light guideplate 3. Further, a diffuser sheet 5 for uniformly diffusing light isplaced on the light guide plate 3, and prism sheets 6, 7 respectivelyhaving a plurality of triangular linear prisms 8, 9 to collect scatteredlight are sequentially placed on the diffuser sheet 5. Two prism sheets6, 7 are disposed so that linear prisms 8, 9 are perpendicular to eachother, thus collecting light radiated in different directions. On theupper prism sheet 9, a protector sheet 10 for protecting the prisms frombeing scratched and preventing the entry of impurities between theprisms is disposed. The individual constituents are assembled, therebycompleting a backlight unit.

However, because the conventional prism sheet has the prism-shapedprotrusions on one surface thereof, defects caused by scratching of theprism-shaped protrusions and by the entry of small impurities into thevalleys between the prism-shaped protrusions and shatter cracks causedby cutting of the prism-shaped protrusions, attributable to frictionwith the protective sheet, may be generated when the backlight unit isassembled. Hence, even if the backlight unit is carefully assembled,many assembly defects may occur, undesirably decreasing productivity,and furthermore, in the case where defects occur, the manufacturingprocess must be conducted again, resulting in high material cost loss.

Further, problems occur because the diffuser sheet, the prism sheet, andthe protector sheet must be sequentially and separately layered in theassembly process.

SUMMARY

Accordingly, the present invention has been made keeping in mind theabove problems occurring in the related art, and provides adiffuser-integrated prism sheet, in which various optical sheets areintegratedly layered, and thus diffuser layers are formed on the outersurfaces of the prism sheet, and prism-shaped protrusions are formed inthe prism sheet, in order to prevent the prism-shaped protrusions frombeing scratched, prevent the entry of impurities into the valleysbetween the prism-shaped protrusions in the course of assembling abacklight unit, and realize a short assembly time and a simple assemblyprocess, resulting in decreased costs, and also provides a method ofmanufacturing the same.

According to the present invention, a diffuser-integrated prism sheetfor backlight units may comprise a lower diffuser layer having a lightdiffusion structure, a lower layer formed on the upper surface of thelower diffuser layer, a first intermediate layer formed on the uppersurface of the lower layer and having a plurality of prism-shapedprotrusions formed parallel to each other, a second intermediate layerformed on the upper surface of the first intermediate layer, an upperlayer formed on the upper surface of the second intermediate layer, andan upper diffuser layer formed on the upper surface of the upper layerand having a light diffusion structure, wherein an air layer is formedbetween the lower surface of the second intermediate layer and thevalleys of the prism-shaped protrusions of the first intermediate layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view illustrating a conventionalbacklight unit;

FIG. 2 is a perspective view illustrating a diffuser-integrated prismsheet according to a first embodiment of the present invention;

FIG. 3 is a bottom perspective view illustrating the diffuser-integratedprism sheet of FIG. 2, in which the size and density of the protrusionsof the lower diffuser layer are suppressed;

FIG. 4 is a perspective view illustrating a diffuser-integrated prismsheet according to a second embodiment of the present invention;

FIG. 5 is a perspective view illustrating a diffuser-integrated prismsheet according to a third embodiment of the present invention;

FIG. 6 is a perspective view illustrating a diffuser-integrated prismsheet according to a fourth embodiment of the present invention;

FIG. 7 is a perspective view illustrating a diffuser-integrated prismsheet according to a fifth embodiment of the present invention;

FIG. 8 is a perspective view illustrating a diffuser-integrated prismsheet according to a sixth embodiment of the present invention;

FIG. 9 is a perspective view illustrating a diffuser-integrated prismsheet according to a seventh embodiment of the present invention;

FIG. 10 is a perspective view illustrating a diffuser-integrated prismsheet according to an eighth embodiment of the present invention;

FIG. 11 is a perspective view illustrating a diffuser-integrated prismsheet according to a ninth embodiment of the present invention;

FIG. 12 is a perspective view illustrating a diffuser-integrated prismsheet according to a tenth embodiment of the present invention;

FIG. 13 is a perspective view illustrating a diffuser-integrated prismsheet according to an eleventh embodiment of the present invention;

FIG. 14 is a perspective view illustrating a diffuser-integrated prismsheet according to a twelfth embodiment of the present invention;

FIG. 15 is a flowchart illustrating a process of manufacturing thediffuser-integrated prism sheet according to the first embodiment of thepresent invention;

FIG. 16 is a flowchart illustrating a process of manufacturing thediffuser-integrated prism sheet according to the second embodiment ofthe present invention;

FIG. 17 is a flowchart illustrating a process of manufacturing thediffuser-integrated prism sheet according to the fifth embodiment of thepresent invention;

FIG. 18 is a flowchart illustrating a process of manufacturing thediffuser-integrated prism sheet according to the ninth embodiment of thepresent invention, and

FIG. 19 is a flowchart illustrating a process of manufacturing thediffuser-integrated prism sheet according to the eleventh embodiment ofthe present invention.

DETAILED DESCRIPTION

Hereinafter, a detailed description will be given of the preferredembodiments of the present invention with reference to the appendeddrawings.

FIG. 2 is a perspective view illustrating a diffuser-integrated prismsheet according to a first embodiment of the present invention.

As illustrated in FIG. 2, the diffuser-integrated prism sheet accordingto the first embodiment of the present invention comprises a lowerdiffuser layer 110, a lower layer 120, a first intermediate layer 130, asecond intermediate layer 140, an upper layer 150, an upper diffuserlayer 160, and an air layer 170.

The lower diffuser layer 110 and the upper diffuser layer 160 havestructures for uniformly diffusing light. Specifically, the lowerdiffuser layer 110 has a plurality of hemispherical protrusions fordiffusing light on the lower surface thereof, and the upper diffuserlayer 160 has a plurality of hemispherical protrusions for diffusinglight on the upper surface thereof.

The height of the protrusions formed on the lower diffuser layer 110 andthe upper diffuser layer 160 ranges from 1 μm to 150 uμ.

As illustrated in FIG. 3, when the density of the protrusions formed onthe lower diffuser layer 110 is suppressed while the height thereof ismaintained to the range from 1 μm to 50 μm, spaces are defined betweenthe protrusions, thereby realizing a non-slip function rather than adiffusion function.

The lower layer 120 and the upper layer 150 are formed of syntheticresin, such as PET (polyethylene terephthalate).

The lower diffuser layer 110, the first intermediate layer 130, thesecond intermediate layer 140, and the upper diffuser layer 160 areformed of a UV light-curable acrylic resin or a heat-curable acrylicresin.

In the first intermediate layer 130, a plurality of prism-shapedprotrusions, cross-sections of which have a triangular shape or apolygonal shape having five or more sides, similar to the triangularshape, is formed parallel to each other, in order to collect light in adirection perpendicular to the upper and lower surfaces of thediffuser-integrated prism sheet.

The ridges 133 of the prism-shaped protrusions of the first intermediatelayer 130 are integrated with the lower surface of the secondintermediate layer 140 through fusion. Further, an air layer 170 isformed between the lower surface of the second intermediate layer 140and the valleys 136 of the prism-shaped protrusions.

The reason why the air layer 170 is formed is as follows. That is,because the refractive index of air is 1 and the refractive index ofmaterial other than air is greater than 1, in the case where the abovespace is filled with material other than air, the effect of collectinglight in the direction perpendicular to the upper and lower surfaces ofthe diffuser-integrated prism sheet is decreased, as per Snell's law.Thus, the intention is to maximize the light collection effect.

Light emitted from the light guide plate is diffused, collected, andthen diffused again, through the prism sheet, which is integratedlylayered with the diffuser sheet to thus exhibit a diffusion function,thereby realizing desired luminance and viewing angle of a backlightunit. This case eliminates the problems with general prism sheets, inwhich scratches occur upon the use thereof and a process of assembling aplurality of optical sheets is complicated, ultimately improving theworkability of assembly of sheets and productivity, resulting indecreased costs.

FIG. 4 is a perspective view illustrating a diffuser-integrated prismsheet according to a second embodiment of the present invention.

As illustrated in FIG. 4, the diffuser-integrated prism sheet accordingto the second embodiment of the present invention comprises a lowerdiffuser layer 210, a lower layer 120, a first intermediate layer 130, asecond intermediate layer 140, an upper layer 150, an upper diffuserlayer 220, and an air layer 170.

The lower diffuser layer 210 and the upper diffuser layer 220 havestructures for uniformly diffusing light. Specifically, the lowerdiffuser layer 210 has a plurality of hemispherical recesses fordiffusing light in the lower surface thereof, and the upper diffuserlayer 220 has a plurality of hemispherical recesses for diffusing lightin the upper surface thereof.

The depth of the recesses formed in the lower diffuser layer 210 and theupper diffuser layer 220 ranges from 1 μm to 150 μm.

As in the lower diffuser layer 110 shown in FIG. 3, when the density ofthe recesses formed in the lower diffuser layer 210 is suppressed whilethe depth thereof is maintained to the range from 1 μm to 50 μm, spacesare defined between the recesses, thereby realizing a non-slip functionrather than a diffusion function.

The lower layer 120, the first intermediate layer 130, the secondintermediate layer 140, the upper layer 150, and the air layer 170 areformed as in the diffuser-integrated prism sheet according to the firstembodiment of the present invention, and a detailed description thereofis thus omitted.

In addition, the diffuser-integrated prism sheet according to thepresent invention may be manufactured in a manner such that the lowerdiffuser layer 210 and the upper diffuser layer 160 are provided asillustrated in FIG. 5 (3^(rd) embodiment), or such that the lowerdiffuser layer 110 and the upper diffuser layer 220 are provided asillustrated in FIG. 6 (4^(th) embodiment).

FIG. 7 is a perspective view illustrating a diffuser-integrated prismsheet according to a fifth embodiment of the present invention.

As illustrated in FIG. 7, the diffuser-integrated prism sheet accordingto the fifth embodiment of the present invention comprises a lowerdiffuser layer 110, a lower layer 120, an intermediate layer 300, anupper layer 150, an upper diffuser layer 160, and an air layer 170.

A small amount of adhesive 320 is applied on the ridges 310 of theprism-shaped protrusions of the intermediate layer 300, and the ridges310 of the prism-shaped protrusions are integrated with the lowersurface of the upper layer 150 through adhesion using the adhesive.Useful adhesives include, for example, highly transparent polymers, suchas silicone-urethane (SU) hybrid polymers, acrylic polymers, andpolyester-based polymers. In the case where too much adhesive is used,the functionality of the prism is weakened, and stain defects may occur.Preferably, the adhesive is used in as small an amount as possible whilestill maintaining adhesion.

The lower diffuser layer 110, the lower layer 120, the upper layer 150,the upper diffuser layer 160, and the air layer 170 are firmed as in thediffuser-integrated prism sheet according to the first embodiment of thepresent invention, and thus a detailed description thereof is omitted.

The diffuser-integrated prism sheet according to the fifth embodiment ofthe present invention may be modified in a manner such that the lowerdiffuser layer 110 and the upper diffuser layer 160 are replaced withthe lower diffuser layer 210 and the upper diffuser layer 220, asillustrated in FIG. 8 (6^(th) embodiment), such that the lower diffuserlayer 210 and the upper diffuser layer 160 are provided as illustratedin FIG. 9 (7^(th) embodiment), or such that the lower diffuser layer 110and the upper diffuser layer 220 are provided as illustrated in FIG. 10(8^(th) embodiments).

FIG. 11 is a perspective view illustrating a diffuser-integrated prismsheet according to a ninth embodiment of the present invention.

As illustrated in FIG. 11, the diffuser-integrated prism sheet accordingto the ninth embodiment of the present invention comprises a PC lowerlayer 400, an upper layer 150, an upper diffuser layer 160, and an airlayer 170.

The PC lower layer 400 is formed of PC (polycarbonate). The uppersurface of the PC lower layer 400 includes a plurality of prism-shapedprotrusions formed parallel to each other, cross-sections of which havea triangular shape or a polygonal shape having five or more sides,similar to the triangular shape, in order to collect light in adirection perpendicular to the upper and lower surfaces of the flatprism sheet. The lower surface thereof includes a plurality ofhemispherical protrusions for diffusing light.

The height of the protrusions firmed on the PC lower layer 400 rangesfrom 1 μm to 150 μm.

As in the lower diffuser layer 110 shown in FIG. 3, when the density ofthe protrusions formed on the PC lower layer 400 is suppressed while theheight thereof is maintained to the range from 1 μm to 50 μm, spaces aredefined between the protrusions, thereby realizing a non-slip functionrather than a diffusion function.

Further, a small amount of adhesive 420 is applied on the ridges 410 ofthe prism-shaped protrusions of the PC lower layer 400, and the ridgesof the prism-shaped protrusions are integrated with the lower surface ofthe upper layer 150 through adhesion using the adhesive. Usefuladhesives include, for example, highly transparent polymers, such assilicone-urethane (SU) hybrid polymers, acrylic polymers, andpolyester-based polymers. In the case where too much adhesive is used,the functionality of the prism is weakened, and stain defects may occur.Preferably, the adhesive is used in as small an amount as possible whilestill maintaining adhesion.

The upper layer 150, the upper diffuser layer 160, and the air layer 170are formed as in the diffuser-integrated prism sheet according to thefirst embodiment of the present invention, and thus a detaileddescription thereof is omitted.

The diffuser-integrated prism sheet according to the ninth embodiment ofthe present invention may be modified in such a manner that the upperdiffuser layer 160 is replaced with the upper diffuser layer 220, asillustrated in FIG. 12 (10^(th) embodiment).

FIG. 13 is a perspective view illustrating a diffuser-integrated prismsheet according to an eleventh embodiment of the present invention.

As illustrated in FIG. 13, the diffuser-integrated prism sheet accordingto the eleventh embodiment of the present invention comprises a PC lowerlayer 500, an upper layer 150, an upper diffuser layer 160, and an airlayer 170.

The PC lower layer 500 is formed of PC (polycarbonate). The uppersurface of the PC lower layer 500 includes a plurality of prism-shapedprotrusions formed parallel to each other, cross-sections of which havea triangular shape or a polygonal shape having five or more sides,similar to the triangular shape, in order to collect light in adirection perpendicular to the upper and lower surfaces of the flatprism sheet. The lower surface thereof includes a plurality ofhemispherical recesses for diffusing light.

The depth of the recesses formed in the PC lower layer 500 ranges from 1μm to 150 μm.

A small amount of adhesive 520 is applied on the ridges 510 of theprism-shaped protrusions of the PC lower layer 500, and the ridges ofthe prism-shaped protrusions are integrated with the lower surface ofthe upper layer 150 through adhesion using the adhesive. Usefuladhesives include, for example, highly transparent polymers, such assilicone-urethane (SU) hybrid polymers, acrylic polymers, andpolyester-based polymers. In the case where too much adhesive is used,the functionality of the prism is weakened, and stain defects may occur.Preferably, the adhesive is used in as small an amount as possible whilestill maintaining adhesion.

The upper layer 150, the upper diffuser layer 160, and the air layer 170are formed as in the diffuser-integrated prism sheet according to thefirst embodiment of the present invention, and a detailed descriptionthereof is thus omitted.

The diffuser-integrated prism sheet according to the eleventh embodimentof the present invention may be modified in such a manner that the upperdiffuser layer 160 is replaced with the upper diffuser layer 220, asillustrated in FIG. 14 (12^(th) embodiment).

Turning to FIG. 15, there is a flowchart illustrating the process ofmanufacturing the diffuser-integrated prism sheet according to the firstembodiment of the present invention.

The method of manufacturing the diffuser-integrated prism sheetaccording to the first embodiment comprises applying a UV light-curableacrylic resin or a heat-curable acrylic resin in an uncured state to apredetermined thickness on the lower surface of the lower layer 120(S110); passing the lower layer 120 having the uncured acrylic resinapplied on the lower surface thereof over a roll having a plurality ofhemispherical recesses and in contact therewith to thus form an uncuredacrylic, resin layer having a plurality of hemispherical protrusions,and then radiating UV light or applying heat to thus completely cure theuncured acrylic resin layer having the plurality of hemisphericalprotrusions, thereby forming the lower diffuser layer 110 (S120);applying a UV light-curable acrylic resin or a heat-curable acrylicresin in an uncured state to a predetermined thickness on the uppersurface of the lower layer 120 (S130); passing the lower layer 120having the uncured acrylic resin applied on the upper surface thereofover a roll having prism-shaped recesses and in contact therewith tothus form an uncured acrylic resin layer having prism-shapedprotrusions, and then radiating UV light or applying heat to thuscompletely cure the uncured acrylic resin layer having the prism-shapedprotrusions, thereby forming the first intermediate layer 130 (S140);applying a UV light-curable acrylic resin or a heat-curable acrylicresin in an uncured state to a predetermined thickness on the uppersurface of the upper layer 150 (S150); passing the upper layer 150having the uncured acrylic resin applied on the upper surface thereofover a roll having a plurality of hemispherical recesses and in contacttherewith to thus form an uncured, acrylic resin layer having aplurality of hemispherical protrusions, and then radiating UV light orapplying heat to thus completely cure the uncured acrylic resin layerhaving the plurality of hemispherical protrusions, thereby forming theupper diffuser layer 160 (S160); applying a UV light-curable acrylicresin or a heat-curable acrylic resin in an uncured state to apredetermined thickness on the lower surface of the upper layer 150 tothus form an uncured acrylic resin layer, and then bringing the lowerlayer 120 into close contact with the upper layer 150 so that the ridgesof the prism-shaped protrusions of the first intermediate layer 130 comeinto contact with the uncured acrylic resin layer of the upper layer150, under pressure the magnitude of which is set so that the ridges ofthe prism-shaped protrusions of the first intermediate layer 130 are notbrought into direct contact with one surface of the upper layer 150 butslightly overlap with the uncured acrylic resin layer of the upper layer150, in a state in which the lower layer 120 is positioned on the upperlayer 150 such that the uncured acrylic resin applied on the upper layer150 does not flow down along the prism-shaped protrusions of the firstintermediate layer 130 (S170); and radiating UV light or applying heatto thus completely cure the uncured acrylic resin layer of the lowersurface of the upper layer 150, thereby forming the second intermediatelayer 140 (S180).

FIG. 16 is a flowchart illustrating a process of manufacturing thediffuser-integrated prism sheet according to the second embodiment ofthe present invention.

The method of manufacturing the diffuser-integrated prism sheetaccording to the second embodiment comprises applying a UV light-curableacrylic resin or a heat-curable acrylic resin in an uncured state to apredetermined thickness on the lower surface of the lower layer 120(S210); passing the lower layer 120 having the uncured acrylic resinapplied on the lower surface thereof over a roll having a plurality ofhemispherical protrusions and in contact therewith to thus form anuncured acrylic resin layer having a plurality of hemisphericalrecesses, and then radiating UV light or applying heat to thuscompletely cure the uncured acrylic resin layer having the plurality ofhemispherical recesses, thereby forming the lower diffuser layer 210(S220); applying a UV light-curable acrylic resin or a heat-curableacrylic resin in an uncured state to a predetermined thickness on theupper surface of the lower layer 120 (S230), passing the lower layer 120having the uncured acrylic resin applied on the upper surface thereofover a roll having prism-shaped recesses and in contact therewith tothus form an uncured acrylic resin layer having prism-shapedprotrusions, and then radiating UV light or applying heat to thuscompletely core the uncured acrylic resin layer having the prism-shapedprotrusions, thereby forming the first intermediate layer 130 (S240);applying a UV light-curable acrylic resin or a heat-curable acrylicresin in an uncured state to a predetermined thickness on the uppersurface of the upper layer 150 (S250); passing the upper layer 150having the uncured acrylic resin applied on the upper surface thereofover a roll having a plurality of hemispherical protrusions and incontact therewith to thus form an uncured acrylic resin layer having aplurality of hemispherical recesses, and then radiating UV light orapplying heat to thus completely cure the uncured acrylic resin layerhaving the plurality of hemispherical recesses, thereby forming theupper diffuser layer 220 (S260); applying a UV light-curable acrylicresin or a heat-curable acrylic resin in an uncured state to apredetermined thickness on the lower surface of the upper layer 150 tothus form an uncured acrylic resin layer, and then bringing the lowerlayer 120 into close contact with the upper layer 150 so that the ridgesof the prism-shaped protrusions of the first intermediate layer 130 comeinto contact with the uncured acrylic resin layer of the upper layer150, under pressure the magnitude of which is set so that the ridges ofthe prism-shaped protrusions of the first intermediate layer 130 are notbrought into direct contact with one surface of the upper layer 150 butslightly overlap with the uncured acrylic resin layer of the upper layer150, in a state in which the lower layer 120 is positioned on the upperlayer 150 such that the uncured acrylic resin applied on the upper layer150 does not flow down along the prism-shaped protrusions of the firstintermediate layer 130 (S270); and radiating UV light or applying heatto thus completely cure the uncured acrylic resin layer of the lowersurface of the upper layer 350, thereby forming the second intermediatelayer 140 (S280).

FIG. 17 is a flowchart illustrating a process of manufacturing thediffuser-integrated prism sheet according to the fifth embodiment of thepresent invention.

The method of manufacturing the diffuser-integrated prism sheetaccording to the fifth embodiment comprises applying a UV light-curableacrylic resin or a heat-curable acrylic resin in an uncured state to apredetermined thickness on the lower surface of the lower layer 120(S310); passing the lower layer 120 having the uncured acrylic resinapplied on the lower surface thereof over a roll having a plurality ofhemispherical recesses and in contact therewith to thus form, an uncuredacrylic resin layer having a plurality of hemispherical protrusions, andthen radiating UV light or applying heat to thus completely cure theuncured acrylic resin layer having the plurality of hemisphericalprotrusions, thereby forming the lower diffuser layer 110 (S320);applying a UV light-curable acrylic resin or a heat-curable acrylicresin in an uncured state to a predetermined thickness on the uppersurface of the lower layer 120 (S330); passing the lower layer 120having the uncured acrylic resin applied on the upper surface thereofover a roll having prism-shaped recesses and in contact therewith tothus form an uncured acrylic resin layer having prism-shapedprotrusions, and then radiating UV light or applying heat to thuscompletely cure the uncured acrylic resin layer having the prism-shapedprotrusions, thereby forming the intermediate layer 300 (S340); applyinga UV light-curable acrylic resin or a heat-curable acrylic resin in anuncured state to a predetermined thickness on the upper surface of theupper layer 150 (S350); passing the upper layer 150 having the uncuredacrylic resin applied on the upper surface thereof over a roll having aplurality of hemispherical recesses and in contact therewith to thusform an uncured acrylic resin layer having a plurality of hemisphericalprotrusions, and then radiating UV light or applying heat to thuscompletely cure the uncured acrylic resin layer having the plurality ofhemispherical protrusions, thereby forming the upper diffuser layer 160(S360); applying an adhesive 320 on the ridges 310 of the prism-shapedprotrusions of the intermediate layer 300, and then bringing the lowerlayer 120 into close contact with the upper layer 150 such that theridges of the prism-shaped protrusions thereof come into contact withthe upper layer 150 (S370); and drying the adhesive 320 applied on theintermediate layer 300.

FIG. 18 is a flowchart illustrating a process of manufacturing thediffuser-integrated prism sheet according to the ninth embodiment of thepresent invention.

The method of manufacturing the diffuser-integrated prism sheetaccording to the ninth embodiment comprises passing a PC lower layer 400formed of PC between an upper roll having prism-shaped recesses and alower roll having a plurality of hemispherical recesses to thus form thePC lower layer 400 having prism-shaped protrusions on the upper surfacethereof and a plurality of hemispherical protrusions on the lowersurface thereof, and then radiating UV light or applying heat to thuscure the PC lower layer 400 (S410); applying a UV light-curable acrylicresin or a heat-curable acrylic, resin in an uncured state to apredetermined thickness on the upper surface of the upper layer 150(S420); passing the upper layer 150 having the uncured acrylic resinapplied on the upper surface thereof over a roll having a plurality ofhemispherical recesses and in contact therewith to thus form an uncuredacrylic resin layer having a plurality of hemispherical protrusions, andthen radiating UV light or applying heat to thus completely cure theuncured acrylic resin layer having the plurality of hemisphericalprotrusions, thereby forming the upper diffuser layer 160 (S430);applying an adhesive 420 on the ridges 410 of the prism-shapedprotrusions of the PC lower layer 400, and then bringing the PC lowerlayer 400 into close contact with the upper layer 150 so that the ridgesof the prism-shaped protrusions of the PC lower layer 400 come intocontact with the upper layer 150 (S430); and drying the adhesive 420applied on the PC lower layer 400.

FIG. 19 is a flowchart illustrating a process of manufacturing thediffuser-integrated prism sheet according to the eleventh embodiment ofthe present invention.

The method of manufacturing the diffuser-integrated prism sheetaccording to the eleventh embodiment comprises passing a PC lower layer500 formed of PC between an upper roll having prism-shaped recesses anda lower roll having a plurality of hemispherical protrusions to thusform the PC lower layer 500 having prism-shaped protrusions on the uppersurface thereof and a plurality of hemispherical recesses in the lowersurface thereof, and then radiating UV light or applying heat to thuscure the PC lower layer 500 (S510); applying a UV light-curable acrylicresin or a heat-curable acrylic resin in an uncured state to apredetermined thickness on the upper surface of the upper layer 150(S520); passing the upper layer 150 having the uncured acrylic resinapplied on the upper surface thereof over a roll having a plurality ofhemispherical recesses and in contact therewith to thus form an uncuredacrylic resin layer having a plurality of hemispherical protrusions, andthen radiating UV light or applying heat to thus completely cure theuncured acrylic resin layer having the plurality of hemisphericalprotrusions, thereby forming the upper diffuser layer 160 (S530);applying an adhesive 520 on the ridges 510 of the prism-shapedprotrusions of the PC lower layer 500, and then bringing the PC lowerlayer 500 into close contact with the upper layer 150 so that the ridgesof the prism-shaped protrusions of the PC lower layer 500 come intocontact with the upper layer 150 (S530); and drying the adhesive 520applied on the PC lower layer 500.

As described hereinbefore, the present invention provides adiffuser-integrated prism sheet for backlight units and a method ofmanufacturing the same. According to the present invention, because theprism sheet includes prism-shaped protrusions forced therein anddiffuser layers integrated therewith, the defect rates attributable toscratching and the entry of impurities in the course of assembling abacklight unit can be drastically decreased. Further, the generation ofshatter cracks by friction with other sheets can be decreased, thusimproving workability, and accordingly, defect rates can be greatlydecreased, resulting in improved productivity. Moreover, various opticalsheets are integratedly layered, thus realizing a short assembly timeand a simple assembly process, resulting in decreased costs.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

1. A diffuser-integrated prism sheet for backlight units, comprising: alower diffuser layer, having a light diffusion structure formed on alower surface thereof; a lower layer, formed on an upper surface of thelower diffuser layer; a first intermediate layer, formed on an uppersurface of the lower layer and having a plurality of prism-shapedprotrusions formed parallel to each other; a second intermediate layer,formed on an upper surface of the first intermediate layer; an upperlayer, formed on an upper surface of the second intermediate layer; andan upper diffuser layer, formed on an upper surface of the upper layerand having a light diffusion structure formed on an upper surface of theupper diffuser layer, wherein an air layer is formed between a lowersurface of the second intermediate layer and valleys of the prism-shapedprotrusions of the first intermediate layer, and the first intermediatelayer and the second intermediate layer are integrated with each otherthrough fusion, and wherein the light diffusion structure formed on thelower surface of the lower diffuser layer comprises a plurality ofhemispherical protrusions for diffusing light.